Mrs. Pilfer, the owner of an independent book store, needs to decide how many copies to order for a new book, Diary of a Wimpy Kid. Retail price is $20 and the wholesale price is $12. Leftover copies are returned to the publisher to get full refund. But she incurs a $4 S&H fee per copy. Demand follows a normal distribution with mean 200 and standard deviation 80. How many copies should she order